Play-minimizing means for adjustable gauging members



Aug. 17, 1948. w J DARMODY 2,447,000

PLAY-MINIMIZING MEANS FOR ADJUSTABLE GAUGING MEMBERS Filed June 7, 1946 Mum.

gwucz/wbm WILLIAM .J. DARMUDY Patented Aug. 17, 1948 UNITED STATES PATENT OFFICE PLAY-MINIMIZING MEANS FOR ADJUST- ABLE GAUGING DIEMTBERS (Granted under the act of March 3, 1883, as amended April 30, 1928; 370 O. G. 757) 4 Claims.

The invention described herein may be manufactured and used by or for the Government for govern-mental purposes, without the payment to me of any royalty thereon.

My invention relates to adjustable snap and other gages and it has particular reference to locking devices employed for maintaining the adjustable gaging members in fixed position.

Broadly stated, the object of my invention is to improve the design and extend the usefulness of adjustable snap and other gages by enhancing their accuracy.

A more specific object is to provide improved means for securing the adjustable snap gaging members in fixed position so as to reduce the amount of their movements or play.

Another object is to provide such improved securing means with the capacity for interchangeable application to any standardized series of adjustable snap gages such as those popularly termed American gage design standard.

A further object is to provide the foregoing improvements with a minimum expenditure of labor, time and funds.

In practicing my invention I attain the foregoing and other objects and advantages by uniquely modifying the shank extremity of standard gaging pins or buttons, and combining therewith a locking Wedge in a novel manner presently to be described. 7 Two preferred forms of my improved device are shown by the accompanying drawings wherein:

Fig. 1 is a side view of a conventional adjustable snap gage showing two different types of my improved locking device installed in the bores of a standard C-shapedgage frame;

Fig. 2 is a section on line 2-2 of Fig. 1 showing how downward pressure of my unique locking wedge upon the gaging members shank minimizes the latters movement by forcing it laterally against the gage frames bore wall; and

Fig. 3 is a section on line 3-3 of Fig. 1 showing the effectively operative positions of the locking screw, bushing and nut of a conventional gaging member locking device.

Gages with, which play-minimizing means are usable Adjustable snap and other gages of a wide variety may be benefited by my improved playminimizing means. Typical of such gages are those specified by the American Gage Design Committee as American gage design standar a number of styles of which are described and illustrated in the U. S. National Bureau of Stand- 2 ards publication Gage Blanks, Commercial Standard C8841, issued in 1941.

The adjustable snap gage shown in Fig. 1 is i1- lustrative of those standard gages. It comprises a c-shaped frame 23, one arm of which contains parallel twin bores 24A and MB for insertion therein of gaging buttons HA and HB, respectively, the other arm supporting an anvil 22, all as shown in the drawing.

The longitudinal axes of the bores 24A and 24B and the longitudinal axes of the gaging buttons HA and B inserted therein are perpendicular to the fiat upper surface of anvil 22. Conventionally, the gaging buttons are fixed in position within the bores so that the flat under surfaces i3A and B3 of the buttons lower flanged portions are within predetermined gaging distances from the anvil. This is done by first removing the anvil, then inserting the shanks of buttons l IA and l IB upwards into the respective bores 24A and 24B for each, and finally tightening the conventional locking screws I8A and I8B to secure the buttons in desired positions.

Thus fixed, the gage is set to test the thickness of objects for acceptance within prescribed limitations by the go or "no go method. A bar, cylinder, sheet or other object is brought within the space separating the anvil 22 and button gaging surfaces l3. To be acceptable within the allowable tolerances, the object being gaged must be able to pass by the go element (gaging button I IB) and not pass the not go element (gaging button HA), while remaining in constant contact with the fiat upper surface of the anvil 22. Passage by both elements HA and B, or failure to pass by the first gaging button I IB indicates that the object being gaged is respectively under or over desired dimensional limitations.

Setting of the gaging buttons HA and B to the desired distances from the anvil 22 is normally done by the following procedure. A standard test block (such as a precision gage block well known to the art and therefore not shown here) having the desired not go dimension is placed between the flat under surface of flange be situated too far up within bore 24A, an ad-.

justing screw IBA may be tightened to gradually urge the button down to the required position before being made fast by locking screw I8A. j

A duplicate procedure is followed for setting the other gaging element, the standard test block being used is one having the desired go dimension, and adjusting screw I63 and locking screw 83 being similarly used to fasten gaging button MB in its required position.

The same technique applies for gages using gaging pins (not shown) which are substantially the same as the illustrated gaging buttons, but

do not have the flanged portions immediately above surfaces I 3A and I3B; Likewise, too, the described technique is usable with gages not having a C-shaped frame, with gaging buttons having square or round heads, and with C-frame snap gages which dispense with the anvil and use gaging pins or buttons on both arms.

The gaging-accuracy problem to be solved One of the most important requirements for successful operation of adjustable snap gages is that the opposing gaging surfaces should remain as perfectly parallel to each other as possible. Referring to the illustrative gage in Fig. 1, this means that it is essential for the fiat under flange surfaces 3A and I313 to parallel the flat upper surface of anvil 22 at all times. Should either of the gaging buttons I-iA or IIB become cocked in their respective bores so as to distort this parallelism, it is obvious that the gage will not function accurately. Such cocking action would tend to diminish the distance between the flat under surfaces HA .and I33 of the flanges and the top of the anvil, thereby altering the go or not go gaging limitations. Erroneous gaging results then would naturally be forthcoming.

Gage manufacturers have aimed to prevent such cocking action from taking place by making the shanks of gaging membersIIA and IIB fit within bores 24A and 243 as tightly as extremely careful machining could make possible. When such a metal-to-metal fit was obtained the undesirable cocking action was of negligible concern. But in the course of large-scale production such closely fitted relationships are expensively time-consuming and their attainment requires a very high degree of mechanical skill. Hence, for the very practical reasons of reducing costs, the standards were lowered by setting certain maximum bore diameter and minimum shank diameter tolerances within which it has been believed an allowable maximum of the described cocking action will not be exceeded.

To minimize this cooking of the gaging member, reliance has heretofore been further placed upon the conventional locking screw I8, locking bushing I9 and locking nut (see Fig. 3). However, although this prior art gaging member locking device has minimized the cocking action, it frequently happens that the device actually causes such mis-alignment conditions due to varying torques exerted on the locking screws I8 as the locking bushings I9 and the locking nuts 20 bear against the shanks of the gaging members IIA and HE.

I Failure of the prior art locking device to entirely eliminate cocking of the gaging members in the gage frame bores has long caused a need for an additional means which will, for all practical purposes, correct this condition. This need has been thoroughly satisfied by my improvement. As evidence thereof are the results of actual tests in which various thicknesses were gaged with a conventional snap gag-e, and one which was improved with my unique device. It

4 was shown that with my novel device variations in distances between the parallel flange under surfaces I3A-I3B and the upper surface of anvil 22 do not exceed 0.00005 inch. This constitutes a significant accuracy advance over the unimproved prior. art gage which gave errors of 0.0004 inch.

The play-minimizing means of my invention In the Fig. 1 illustration two forms of my improved play-minimizing means for gaging members are shown. In each case, the shank of the existing standard gaging button IIA or IIB has had the unfianged extremity modified, a slanted or angular out. having been made on each one as shown. The plane of these cuts most preferably is one about mid-way between a transverse and a longitudinal section of the shanks, and best should pass through a sizeable portion of the shanks diameter. (In the shank of button IIA, the slanting out has gone through most of the diameter; in the shank of button I IE, only about half-way.) At each end of these cuts, a fiat portion is made as shown to parallel the original fiat upper surface of the shank for reasons which will soon become apparent.

A wedge-like plug I5A or IE3 is inserted into the respective bores IGA and IBB as shown in Fig. 1. These plugs are preferably designed so that their diameters fit rather snugly within the gage frame bores. Furthermore, as the drawing shows, the plugs under surfaces are angularly cut, and with flat partions on each end of the cut, in a manner similar to the cuts made in the corresponding gaging button shanks with which they are intended to mate. When placed in proper mating relationship the angular cuts on the plugs I5 and the shanks of buttons I I present a continuous slanting line of contact with each other represented by 25, while serving together to fill the bore 24 as shown by the Fig. 2 section through both parts. 7

It should be noted by comparison of Figs. 2 and 3 that the contact line 25 between plug I5 and the shank of button II is parallel to the long axis of the prior art locking screw I8, locking bushing I9 and locking nut 20. The importance of maintaining this parallel relationship for optimum results will become obvious with an understanding of my unique locking device's action. But the net result of keeping this parallel status should now be quite clear: The direction in which the forces of the conventional locking device I8 'I920 act to fasten the shank of button II is perpendicular to the long axis of locking screw 18 (see Fig. 3); for maximum locking support in supplement to this prior art lock, my new device preferably should act in the same general direction. This actually occurs as reference to Figs. 1-2 will show. As the wedging plugs I5 are forced downwardly to press against shanks II, the tendency is for them to push the angular shank extremities laterally against the same bore sidewalls as do the conventional locking devices lower down.

Installation of the novel wedging plugs ISA and I5B'1s simple; it merely requires dropping them through the respective bores 24A and 24B so that the angular cuts thereon mate with their counterparts on 'the shanks of buttons HA and IiB. The use of these plugs to lock the upper extremities of the shanks against movement, just as do the conventional locking devices for the lower .endsof the sharks, involves no special technique or procedure thereafter. The gaging -members, buttons HA and I I3 and the anvil- 22,

are set the prescribed distances apart with the aid -of standard blocks or other well known means; the adjusting screws ISA and I613 can be tightened in bores 24A and 243 as per usual; and final tightening of the conventional locking devices l8l9--2l can then be made.

It Will be noted that no change to the gage frame 23, the bores 24, the anvil 22, the old type locking device, or the adjusting screws I6 has been described; this is because no changes to any of these parts are required. Thus, my improvement is usable \m'thout any modification to standard gages with the sole exception of the angular cut in the extremity of the gaging button shank II, a very simple change to make in all standard gaging button (or gaging pin) shanks. This one change, plus the addition of the wedge-shaped plugs are of small consequence with regard to the cost, time and labor involved, when compared with the vast improvement in gaging accuracy which is had thereby.

As earlier indicated, designers practicin my invention should be careful to leave a fiat portion on at least one and preferably both ends of the aforementioned angular cuts on both the plugs I5 and the shanks of buttons ii. The reasons for this should by this point be quite evident. When placed together as in Fig. l, the matching flat portions of the opposing plugs and shanks combine to form notch-like cavities between the two as shown. These cavities enable the plugs l5 to be forcibly urged against the shanks H at the line of contact 25 between the two parts by tightening the adjusting screws l6. Without these cavities, no more pressure could be had to direct the shanks lateral-wise against the bore 24 sidewalls into locking relationship therewith than would be possible when the adjusting screws were tightened against the prior art shanks not possessing my unique modifications.

The accompanying illustrations show only two forms representative of my novel improvements. Optionally, however, my invention can be practiced in other ways without changing the spirit, intent and scope thereof, as should be obvious to all those skilled in the art of gage manufacture.

Summary From the foregoing it will be seen that I have improved the design and extended the usefulness of adjustable snap gages by enhancing their accuracy; that I have provided improved means for securing adjustable snap gaging members in fixed position so as to reduce the amount of their movement or play; that I have provided such improved securing means with the capacity for interchangeable application to any standardized series of adjustable snap gages such as those popularly termed American gage design standard; and that I have provided the foregoing improvements with a minimum expenditure of labor, time and funds.

. My invention is therefore broad in its adaption and hence is not to be restricted to the specific forms here shown by Way of illustration.

I claim:

1. In an adjustable gaging device comprising an arm having a bore opening therethrough, the combination of a stem member movably fitted into said bore opening with one end thereof protruding from the arm and presenting a flat gaging surface perpendicular to the axis of said bore and with the opposite stem end terminating within the bore and having a portion of that ends cross section slanted with respect to the stem axis, locking means intermediate said two stem ends adjustably anchorin 'the stem in said bore and restraining same in each anchored position against axial movement with respect to the bore, a plug fitted into the end of said bore farthest away from the stems gaging surface and having a portion of. one of its ends slanted with respect to the plugs axis so as to mate with the slanted portion of said stem members non-gaging surface end in a way to convert axial pressure by the plug against that stem end into a sidewise force which positively urges the slanted stem end against the bore Wall and thereby prevents the stem from cocking in said bore so that the stems gaging face is held perpendicular to the bore axis as aforesaid, and an adjusting screw threadably fitted into said bore behind said plug for the purpose of applyingsaid axial pressure through the plug to the stems said slanted end.

2. In an adjustable gaging device comprising an arm having a bore opening therethrough, the combination of a stem member movably fitted into said bore opening with one end thereof protruding from the arm and presenting a flat gaging surface perpendicular to the axis of said bore and with the opposite stem end terminating within the bore and having a portion of that ends cross section slanted with respect to the stem axis so that the slanted end presents opposing first and second Wall portions of different lengths, locking means intermediate said two stem ends actable upon the said first wall portion of the stem to urge the stems said second wall portion against the wall of said bore adjacent thereto for the purpose of adjustably anchoring the stem within the bore and restraining same in each anchored position against axial movement with respect to the bore, a plug fitted into the end of said bore adjacent to the stems said slanted end and having a portion of one of its ends slanted with respect to the plugs axis so as to mate with the slanted portion of said stem members nongaging surface end in a way to convert axial pressure by the plug against that stem end into a lateral force which positively urges the said second wall portion of the stems slanted end against the bore wall adjacent thereto and thereby prevents the stem from cooking in said bore and assures that the stems gaging face will be held perpendicular to the bore axis as aforesaid, and an adjusting screw threadably fitted into said bore behind said plug for the purpose of applying said axial pressure through the plug to the stems said slanted end.

3. In an adjustable gaging device comprising a C-sh-aped frame having first and second spaced arms that are separated one from the other to provide a gaging aperture between opposing faces of the arms and the first of which arms has a bore opening extending therethrough in a direction perpendicular to the gaging face of said second arm, the combination of a stem member movably fitted into said bore opening in the first arm so that the end thereof closest to said second arm presents a fiat gagin surface parallel to said opposing face of the second arm and having the opposite stem end terminated within the first arm bore with a portion of the stems end crosssection slanted with respect to the stem axis, locking means intermediate said two stem ends adjustably anchoring the stem in said bore and restraining same in each anchored position against axial movement with respect to the bore,

a plug fitted into the end of said bore that is away from said second arm and having one of its ends slanted with respect to the plugs axis so as to mate with the slanted portion of said stem members non-gaging surface end in a way to convert axial pressure by the plug against that stem end into a sidewise force which positively urges the slanted stem end against the bore wall and thereby prevents the stem from cocking in said bore so that the stems gaging face is held parallel to the second arms gaging face as aforesaid, and an adjusting screw threadedly fitted into said bore behind said plug for the purpose of applying said axial pressure through the plug to the stems said slanted end 4. In an adjustable gaging device comprising a C-shaped frame having first and second arms that are separated one from the other to provide a gagin aperture between opposing faces of the arms and the first of which arms has a bore opening extending therethrough in a direction perpendicular to the gaging face of said second arm, the combination of a stem member movably fitted into said bore opening in the first arm so that the end thereof closest to said second arm presents a fiat gaging surface parallel to the gaging face of said second arm and having the opposite stem end terminated within the first arm bore with a portion of the stems end cross section slanted with respect to the stem axis so that the slanted end presents opposing first and second wall portions of difierent lengths, locking means intermediate said two stem ends actable 8 upon the said first wall portion of the stem to :urge the stems said second wall portion against the wall of said bore adjacent thereto for the purpose of adjustably anchoring the stem within the bore and restrainin same in each anchored position against axial movement with respect to the bore, a plug fitted into the end of said bore adjacent to the stems said slanted end and having a portion of one of its ends slanted with respect to the plugs axis so as to mate with the slanted portion of said stem members non-gaging surface end in a way to convert axial pressure by the plug against that stem end into a lateral force which positively urges the said second wall portion of the stems slanted end against the bore wall adjacent thereto and thereby prevents the stem from cooking in said bore and assures that the stems gaging face will be held parallel to the second arms gaging face as aforesaid, and an adjusting screw threadably fitted into said bore behind said plu for the purpose of applying said axial pressure through the plug to the stems said slanted end.

WILLIAM J. DARMODY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,309,700 Sousa July 15, 1919 1,300,841 Johansson Apr. 15, 1919 

